<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>浮层</title>
</head>
<body>
<div class="box">
    <div class="cont">
      <div class="contbox">
            内容
      </div>
    </div>
   <div class="foot">底部</div>
</div>
<style>
  *{
    margin: 0;
    padding: 0;
    font-size: 30px ;
    color: white;
}
  .box{
    position: fixed;
    top: 0;
    left:0;
    width: 100%;
    height: 100%;
    background: pink;
    overflow: auto
  }
  .cont{
    width: 100%;
    min-height: 100%;
    background: blue;
    opacity: 0.3;
  }
  .contbox{
    height: 1000px;
    background: orange;
    padding-bottom: 100px;
  }
  .foot{
    position: relative;
    top:0;
    height: 100px;
    margin-top:-100px;
    background: red;
  }



</style>
</body>
</html>
